Recently, many automatic transmissions have multiple number of gear shift stages. Then, number of frictional clutching elements such as clutches and brakes are increased in accordance with the increase in the number of gear shift stages. In addition, as the number of the gear shift stages are increased, intervals between gear shift lines of a shift map become remarkably dense. Hence, the gear shift is easy to occur due to a slight change in a traveling condition (for example, a throttle opening angle or so forth). That is to say, a frequency of the occurrence of the gear shift is increased so that such a scene that a request to modify a target gear shift stage even while the gear shift occurs is increased.
Therefore, as a conventional technique, in a case where the modification request occurs during the gear shift as described above, such a control apparatus for the automatic transmission that the modification of the target gear shift stage is allowed in a case where the modification request of the target gear shift stage occurs due to the change in the traveling condition at a time from a determination of the gear shift to a start of an actual gear shift, namely, until the start of an inertia phase and, after the start of the inertia phase, the modification of the target gear shift stage is inhibited to complete the gear shift during the gear shift is described in a Patent Document 1.
However, since, in the conventional control apparatus for the automatic transmission, the modification of the target gear shift stage or, so-called, a change mind gear shift is allowed if the modification of the target gear shift is before the start of the inertia phase, a shock and an engine racing are often generated.
That is to say, it is difficult to accurately detect a return quantity of a piston stroke under a release control and a clutch capacity in the frictional clutching element. Therefore, in the frictional clutching element in which control is changed from a release control to an engagement control according to the execution of the change mind gear shift, an actual piston return quantity or the clutch capacity are smaller than the detected piston return quantity or clutch capacity (the piston stroke is not returned from a supposed return quantity), an abrupt engagement is resulted and the shock is generated.In addition, when the actual piston return quantity or the actual clutch quantity is larger than the detected piston return quantity or the clutch capacity, an engagement delay occurs and the engine racing is generated.